Trailers attached to pull vehicles are commonly used to transport machinery, livestock and other goods. When the trailer is unhitched from the pull vehicle, the trailer and its goods are subject to theft by undesired coupling to some other towing or pull vehicle. Trailer hitches are of a limited variety, frequently being of standard types of shapes. Examples are ball and socket hitching devices in which the trailer coupler consists of a socket which mounts on a ball attached to the pull vehicle; kingpin hitches which consist of cylindrical posts containing circumferential recesses and fit into matching openings mounted on the pull vehicle; and gooseneck hitches. The typical or standard trailer hitch consists of a socket attached to the lower end of a generally vertical post extending downwardly from the trailer. The posts and trailer hitches may have a horizontal component or beam at its upper end and which attaches to the front of the trailer. The trailer hitch coupler at the lower end of the post generally connects with a receiving device on the pull vehicle. The coupler itself consists of front and rear facing portions of different shapes and configurations.
To prevent undesired coupling of trailers to other pull vehicles, locks have been devised to fit over the ball or over or within the socket of a ball and socket type hitch. Such locking devices, however, generally have several moving parts and are not easily used or adapted for use with a trailer hitch coupler.
There are several prior art devices for preventing the undesired coupling of trailers to other pull vehicles. For example, F. H. Grinnell et al. U.S. Pat. No. 2,440,744 discloses a circular locking device for a kingpin of an upper fifth wheel plate of a trailer which consists of a locking plate, a locking member and a movable exposed lock. The locking device, when engaged, fits about the kingpin to prevent the kingpin from entering the receiving slot of a fifth wheel.
There is also G. L. Lucas et al. U.S. Pat. No. 2,656,706 which discloses a circular lock collar for trailer kingpins which consists of a split collar lock that includes semianular hinged sections, an annular groove and a key operator lock with a concealed bolt. The split collar device is positioned to enclose the kingpin and two semianular hinged sections are locked together by the concealed bolt of the key operated lock.
Additionally, A. J. Marx U.S. Pat. No. 3,662,320 discloses an electrical plug lock comprising of a frame and a bolt that cooperate to enclose electrical prongs of a plug. A conventional padlock is positioned to lock the frame to the plug.
A. K. Nielsen, Jr. U.S. Pat. No. 4,407,146 discloses a lock assembly that prevents unauthorized disconnection of a gas line from a gas meter. The lock assembly includes a male and a female telescoping shroud having an aligned aperture, a bolt lock and an end cap. The shrouds are positioned to enclose a threaded connection of the gas line to the gas meter. The bolt lock is positioned through the aperture when the shrouds are aligned. The end cap is engaged with the bolt lock to lock the shrouds together.
Additionally, G. A. Watson U.S. Pat. No. 4,444,031 discloses a security locking device for tackle boxes and the like that includes a sleeve member open at one end and closed at the opposite end, with the closed end secured to a permanent structure. The sleeve extends through an aperture of a tackle box. The open end has aligned bores to receive a padlock member that is then locked. D. E. Van Cuyk U.S. Pat. No. 5,052,203 discloses a locking device for a kingpin of a fifth wheel plate to a trailer. The locking device includes a cylindrical cup having a transversely extending slot, a hinged latch that is attached to the cup, aligned apertures in the latch that allows the conventional padlock to be engaged. The cup is positioned around the kingpin and the latch is related to the register within the slot. The latch is then aligned so that the apertures can receive a member of the padlock. The Italy Patent No. 584,555 discloses an elongated locking device with a bore that encloses a circular component that is to be locked. The locking device also has two sliding members with a key lock at the end of the larger of the two members, such that the members are slid together, the bore is then closed around the component. The key lock is then engaged locking the device and closing the component. Finally, the Britain Patent No. 959,271 discloses a key operated locking device associated with containers. The locking device includes a conventional padlock and an external holder adapted to retain the padlock. The holder includes an outer aperture, a bolt and a bracket having a threaded aperture that is attached to the inside of the container. The holder is then positioned over the top of the container. The apertures are aligned and the bolt is inserted through the apertures to attach the holder to the container. The padlock is engaged securing access to the container.
There is an additional prior art, C. Rossi U.S. Pat. No. 2,785,564 that shows a locking device for trailer coupler pin having two hinged mount halves which swing together about the trailer coupler. The halves each have ears with apertures through which a padlock is slipped. Note that in distinction to the structure, there is simply no concealed pins nor is there a removable lock means which prevents access to the concealed pins. Therefore, there is a need for a durable, inexpensive, simply operated, and effective trailer hitch lock for trailers with the locking devices having a singular lock body. Such locking devices should further contain means to prevent its undesirable removal from a coupler.